Computerized visual communication (C-ViC) uses the sequential placement of icons displayed on a computer screen to create sentences, using a visual symbol vocabulary and a left to-right grammar. Since its introduction in the mid- 1980's, it has proven to be usable for two-way communication with global aphasics who were unable to produce or comprehend natural language. In this project we propose the first controlled efficacy study of C-ViC using a structured teaching program developed by Dr. Baker in this Center. The first and second study use a treatment/no treatment cross-over design to evaluate treatment efficacy both in two phases of on site training (Phase I and Phase III and in home training with the spouse as interlocutor (Phase III). The remaining four studies are experimental analyses of several basic cognitive underpinnings of C-ViC. Study 3 uses psychophysical techniques to examine the number of icons per visual presentation field that can be scanned most efficiently by the C-ViC user. Study 4 manipulates the load on working memory to determine the role of this factor in C-ViC use. Study 5 examines the capacity of patients for category identification, in comparison to basic object identification. Both levels of object recognition are intimately involved in the C-ViC process but they do not appear to be equally impaired by severe aphasia. Study 6 - Verb icons are generally harder to use than noun icons, in particular, because most common verbs have many situation-specific meanings that are only conceptually or metaphorically related (e.g. 'open' a box vs 'open' a meeting.) This study examines patients' limits in grasping conceptual extensions of verb meaning.